Laser is an acronym for Light Amplification by Stimulated Emission of Radiation.

In the molecular level, all physical matters have molecules that are surrounded by multiple orbits of electrons. The electrons in the outer orbits carry higher energy levels, but are also more unstable. When a molecule is Stimulated by an external energy, the electrons will absorb this energy and “jump” to higher energy orbits and “store up” this energy.

Since they are unstable in the higher orbits, they will return to the lower orbits after a while, releasing the energy again. In some materials, the released energy in such a process forms a Radiation and is Emitted out. When this process is Amplified to involve hundreds of millions of molecules, and their electrons release the energy simultaneously, this forms a LASER.

Principles Of Laser Treatments

Some materials can be used as mediums to produce lasers by stimulation. These include ruby, dyes, neodymium, alexandrite, carbon dioxide gas, and many others. Different mediums will produce lasers of different wavelengths.

When a laser hits on a target, it may be absorbed and the interaction will produce heat energy, destroying or changing that target’s nature. Each target has a different absorption spectrum of wavelengths, i.e. it absorbs different wavelengths to different degrees. So in order to hit a target strong enough, a laser that is preferentially absorbed by that target should be selected.

We call these targets chromophores. The main chromophores in the skin are water, melanin pigment, cells of blood vessels, and oxygenated blood pigment. They are located in different skin levels, and also have different absorptions to different wavelengths.

When we use lasers with different wavelengths and energy intensities, we can penetrate into different levels, selectively damage different targets. We call this selective photo-thermolysis.

When melanin is hit, for example in the case of freckles, it is shattered into tiny particles, which are then small enough to be removed by cells called macrophages.

The melanin in the hair root is there to attract the laser, and when it is hit, the heat generated will destroy the root so that further hair growth is slowed down.

Similarly, the oxygenated haemoglobin inside the blood vessels is used to attract the laser, and when it is hit, the heat generated will destroy the blood vessels, interrupt the blood flow, and remove the unattractive red and blue lines, and vascular birthmarks.